Soldering a socket on your board

Mainboards where the BIOS chip is soldered onto the board (i.e., not in a socket) are usually problematic for coreboot developers and especially coreboot users, as one incorrectly flashed image will render the board unusable.

Here's a simple procedure how you can desolder/remove the chip from such a board, and solder on a PLCC socket instead (so that you can swap chips as often as you like later on).

Important: This will definitely void the warranty of your board! Also, we take no responsibility for any damage you inflict on your board or other stuff. Use at your own risk!

That said, we believe this procedure requires only relatively low-cost equipment which is widely available, and can also be performed by people without much soldering experience. You do not have to be a hardware/soldering guru to do any of this, with a little practice everyone can learn to perform the procedure.

The desoldering station used here is an Aoyue 852 SMD Rework Station, which is available relatively cheaply (ca. 70.- Euros). There are even cheapers ones available, e.g. on eBay.

Preparation

Take a picture of the board and ROM chip. You might need that later in order to add the socket in the correct orientation. The ROM chips all have a marking where the top is (and the same is true for most boards), but on some boards there is no such marking. So write down the orientation of the chip (or take a picture).

Prepare the PLCC socket, by cutting away the plastic middle part using the wire cutter (for easier soldering later):

Wire cutter and PLCC socket

Cut the middle part

Socket and removed plastic

Prepared socket, back side

Desolder or cut away the ROM chip

The next step is to remove the soldered ROM chip. There are basically two ways to do that.

Desoldering the chip.If you have access to a desoldering station use that for desoldering the chip. Use a temperature of ca. 350-370°C. Higher temperatures might speed up the process a bit, but will also increase the risk of damaging the chip or surrounding parts. At 370°C the process takes less than 20 seconds.

Advantages:

Quick and painless method.

The ROM chip will usually survive, if you're careful and don't supply too much heat.

Disadvantages:

You have to spend some money on a desoldering station (less than 70,- Euros).

Desoldering the chip (Alternate method).You can also use a piece of aluminum foil and a house hold heat gun for desoldering the chip. Most heat guns have a high and low setting, you will only need the low setting. The whole process only takes a few minutes.

Advantages:

Fairly quick and painless as long as you don't burn yourself.

The ROM chip will usually survive, if you're careful and don't supply too much heat.

Disadvantages:

You have to be very careul not to pull on the chip. You could lift a solder pad causing a whole other issue.

The chip is rendered unusable in the process (so make sure you have a backup before cutting it).

Soldered PLCC chip

Desoldering temperature

Hold the chip with tweezers

Desoldering the chip

PCB pads after desoldering

Desoldered chip, front

Desoldered chip, back

1. Use a piece of aluminum foil and fold it in half (for double the protection).

2. Bend the foil over the chip for cut out lines.

3. Cut out a rectangle out just the size of the chip.

4. Foil with chip cut out.

5. Place the foil over the chip.

6. Close up of foil over chip.

7. Blow the heat at an angle to the side of the chip at the solder joints going around the chip in a circle. Never directly on top.

8. After a minute or two the chip will pretty much fall off. Use tweezers to remove.

9. Shot with the foil and chip removed.

10. Another shot of the foil and chip.

11. Close up of the chipless board. Now your ready to clean it up and solder on a socket.

Clean the pads on the board

The next step is to clean the PCB pads, i.e., remove the remains of solder from the pads. Use desoldering wick for that.

Pads before cleaning

Cleaning with desoldering wick

Cleaned pads

Solder the socket onto the board

Now solder the PLCC socket onto the pads. This procedure is best performed manually with a soldering iron (in theory you could try to use a desoldering station / heat gut, but the results are probably not too good, and you might melt the plastic socket). Optionally, if you have some No Clean Flux handy, apply some of it on the pads. This will make the soldering process a bit easier.

We suggest to start by aligning the socket onto the pads with tweezers or with your fingers. Solder two pins in opposite corners of the socket first, in order to fixate the socket. Then solder all the other pins, one after the other. If you apply too much solder and two or more pins get connected accidentally, use the soldering wick to fix that.

Put solder on a pad

Put solder on another pad

Aligning, tweezers

Aligning, fingers

Soldering the socket

Soldered-on socket

Testing the socket

Socket with chip

Results

Congratulations. You have now successfully replaced a soldered-on PLCC ROM chip on your board with a PLCC socket. You can now swap out the ROM chip as often as you want to or need to. In almost all cases, the board and the ROM chip will survive this procedure if you are careful.